Recently, provision of printed materials of various kinds and small lots is under progress, and attention is drawn to, as a substitute for off-set printing of a related art, inkjet printing which is on-demand printing made easy to respond to high speed printing. Furthermore, as compared to conventional off-set printing, the inkjet printing is more convenient and has a merit such as economic value or energy saving.
The inkjet printing is a printing method in which fine ink droplets ejected from a printer head are landed on a recording medium, infiltrated and fixed to form dots, and in accordance with gathering of many of those dots, an image is formed. Accordingly, a printed material is an aggregate of dots that are formed of fine droplets, and thus it is difficult to have an even surface so that poor fixability or scratch resistance may be obtained.
Furthermore, for example, when printing is made on a coated paper having a hydrophobic coating layer formed thereon by using an aqueous ink, it is difficult for the ink to infiltrate into the coated paper. Thus, there is a problem that, as the ink is repelled on a surface of the coated paper and cannot be evenly applied, the printed material tends to have insufficiency in water resistance and solvent resistance.
As a method of fixing an image of a printed material, for example, a method of performing thermocompression bonding by use of a compression bonding roller after an image recording step is known.
Furthermore, in Patent Literature 1, a toner composition for improving light fastness of a printed image and performing water resistant coating by overcoating on an inkjet print is disclosed.
However, those methods cause an increased number of operation processes for inkjet printing, and thus they are unfavorable in terms of having a merit of inkjet printing, such as convenience, economic efficiency, or energy saving.
Meanwhile, a method of adding a wax component, which is conventionally used for a toner, to an inkjet ink is studied (for example, Patent Literatures 2 to 5).
For example, in Patent Literature 2, as a method of improving scratch resistance in the case of recording on a recording medium such as fabrics or resin materials by using an aqueous ink, an inkjet recording method in which ejection is performed while heating an aqueous ink containing a pigment, a fixing resin, and a wax with specific melting point is disclosed.
In Patent Literature 3, an ink composition containing a pigment and a polyolefin wax having a larger particle diameter than dry film thickness, is disclosed as an ink composition with which a recorded image with excellent scratch resistance can be obtained.
In Patent Literature 4, as a scratch resistant inkjet ink composition which hardly causes clogging of an inkjet nozzle, an ink composition containing a pigment, a binder resin, a particulate wax with particle diameter of 0.58 to 3 μm, a moistening agent, and water is disclosed.
Furthermore, in Patent Literature 5, as an image forming method for forming an image with good texture feeling such as touch feeling and excellent scratch resistance, a method of forming an image by applying, based on an inkjet method, an aqueous ink containing polymer particles, a specific amount of wax particles, a colorant, and water on a recording substrate, which is an aggregate of specific fiber materials, is disclosed.
Patent Literature 1: JP 2002-258525 A
Patent Literature 2: JP 2009-291976 A
Patent Literature 3: JP 2005-48108 A
Patent Literature 4: JP 2007-161823 A
Patent Literature 5: JP 2013-82209 A